Response has been good to the PayNow fund transfer system that went live yesterday at 8am.
More than 50,000 users have registered with participating banks as of 5pm yesterday, the Association of Banks said in a statement.
PayNow lets users transfer money to each other using just the recipient's mobile or NRIC number once an account has been linked.
The sender sees the recipient's name before approving the fund transfer.
Mr Aditya Gupta, OCBC Bank's Singapore head of e-business, told The Straits Times: "The initial response to PayNow has been expectedly strong.
"Within the first few hours of launch, close to 15,000 customers have linked their OCBC accounts to their mobile number or NRIC, and we expect the number to grow exponentially in the coming days."
Standard Chartered noted that about 15 per cent of its mobile active customers have registered for PayNow with applications hitting a high early in the morning thanks to its $10 cash bonus promotion for the first 20,000 customers who register.
At DBS, 70 per cent of those who signed up preferred to use mobile numbers.
UOB said it had more than 12,000 registrations in a few hours.
Citibank was unable to provide data.
Maybank is also part of the scheme but it was unable to respond in time.
Mr Usman Khalid, head of payments of Standard Chartered Bank Singapore, said: "As awareness of PayNow increases, we expect these encouraging registration numbers to continue in the next week."
Mr Alvin Lim, digital head at HSBC Bank (Singapore), said: "The response has been encouraging.
"As of 5.30pm (yesterday), the sign-up rate has exceeded our initial expectations since we have just shared (news of) the availability of the new service to our customers."
OCBC's Mr Gupta said customers have been embracing the movement away from cash, evident in OCBC Pay Anyone payment volume, which has increased 10 times since May last year.
"Now, with the added convenience of PayNow integrated with OCBC Pay Anyone, the shift towards cashless payments will receive a huge boost," he added.